This invention relates to a print ribbon cassette for use with a typewriter, printer or like printing office machines.
In a typical one of conventional print ribbon cassettes, a ribbon is wound on a flange supported for rotation in a cassette body and has a beginning end thereof secured to a take-up spool while a required length of the ribbon between the flange and the take-up spool is exposed outside the cassette body so as to be used for printing therewith with a tensile force applied to the ribbon to maintain the exposed portion of the ribbon in taut condition.
For example, a ribbon cartridge disclosed in Japanese laid-open patent No. 57-57687 has a ribbon lock device for causing a required tensile force to be applied to a printing portion of a ribbon, and the ribbon lock device includes a tension element on which ribbon is mounted, a brake blade, and a bellcrank connecting mechanism including a slot, an unlocking member and so on for interconnecting the tension element and the brake blade.
However, such a conventional ribbon cartridge has a drawback in that it includes a large number of parts in its ribbon lock device and is complicated in structure, and hence much time is required to assemble them, resulting in increase in production cost.